They are lens, with correction or not, with different colors and sizes. They help to look your eyes bigger, and change your eyes color. You can find blue, green, violet, pink, ... lens. You can also find small and big size, so you can create really big eyes. Circle lens are wearing for cosplay (ex: sharingan from "Naruto") or fashion. Japanese and Korean girls often wear this kind of lens.

KLenspop is a webshop who sell circle lens. They have a lots of color and design. And they often have new ones. Their lens are from Korean brands. They also have some cosmetics and accessories. I received lens from this shop from a few time now, and I'm always happy with them. They have good quality products and are really nice. I generally received my lens after 2 or 3 weeks.